The present invention relates to an area type light emitting device and a manufacturing method thereof, which are used for a transmission type display unit that does not emit light for itself such as a liquid crystal display (LCD) unit.
An area type light emitting device is required to have important factors, such as a low cost, not having non-uniformity of brightness, and having a high luminance. FIG. 1 is a sectional view of a conventional area type light emitting device. As shown in FIG. 1, the conventional area type light emitting device consists of a light source 100, a reflector 102, and a light guide unit 201. And the light guide unit 201 consists of a light guide component 202, a diffusion component 204, a reflection component 206, a reflection pattern 208, and an adhesive 210.
At the conventional light guide unit 201, the reflection pattern 208, which makes emitted light from the light source 100 reflect irregularly or regularly, is formed by transferring a pattern used a screen printing on the reverse side (the side existing the reflection component 206) of the light guide component 202. Or the reflection pattern 208 is formed on the light guide component 202 by that the reflection pattern 208 is also formed in a molding die forming the light guide component 202.
However, at this conventional light guide unit 201, the reflection component 206 is fixed to the light guide component 202 by using the adhesive 210 such as a both sides adhesive tape on the edge sides of the reflection component 206. Consequently, displacement, bending, and deformation of the reflection component 206 occur for the light guide component 202 under a high temperature environment. Therefore, this is not enough for keeping good quality.
Japanese Patent Application Laid-Open No. HEI 4-191704 discloses an area type light emitting device and a manufacturing method thereof In this application, a transparent pattern adhesive layer, which is a reflection pattern whose reflection area becomes larger corresponding to farther the distance from a light source, is provided between a light guide component and a reflection component. And this transparent pattern adhesive layer works as the reflection pattern of the reverse side of the light guide component and also works as a means for fixing the reflection component to the light guide component. Therefore, this structure is effective for reducing a cost and for decreasing the non-uniformity of the brightness of the area type light emitting device.
However, this area type light emitting device uses an adhesive means as a fixing means for fixing the reflection component to the light guide component, therefore, the non-uniformity of the brightness occurs depending on the condition of environment, that is, the problem at the conventional method is not solved completely. This conventional method uses an adhesive whose main material is a resin as the transparent pattern adhesive layer. Consequently, for example, at a high temperature environment, this adhesive is softened and the reflection component is displaced or deformed by its own weight or its structure for the light guide component, as a result, a non-uniform gap occurs between the light guide component and the reflection component.
FIG. 2 is a perspective view of a disassembled LCD unit used an area type light emitting device. As shown in FIG. 2, the LCD unit provides a LCD panel unit 300, a front bezel 302, an area type light emitting device 200, and a frame 304, and the frame 304 has an opening part 306. In order to reduce the total weight of the LCD unit, there is a case that the frame 304 holding the area type light emitting device 200 is formed as a rectangular frame. Therefore, the reflection component 206 is displaced or deformed in the opening part 306 of the frame 304 by a high temperature environment and this causes a problem that hazy nonuniformity or an extraordinary bright part being a bright spot state occurs on the LCD unit.
Further, at the manufacturing process of this area type light emitting device, there is a process to fix the reflection component 206 to the light guide component 202 by using an adhesive, or a process to form a reflection pattern by printing in addition to a process to fix the reflection component 206 to the light guide component 202. Therefore, the manufacturing cost will not be reduced largely.
It is therefore an object of the present invention to provide an area type light emitting device and a manufacturing method thereof, in which a reflection component can be firmly fixed to a light guide component and the manufacturing cost can be reduced.
According to a first aspect of the present invention, at an area type light emitting device, in which a reflection component is disposed on the reverse face of a transparent light guide component, and also a light source is disposed at the side of said transparent light guide component, makes light emit from the surface of said transparent light guide component by that emitted light from said light source is inputted to said transparent light guide component and said inputted light is reflected on said reflection component and said reflected light is passed through said surface of said transparent light guide component, at the time when a reflection pattern, which makes said emitted light from said light source reflect to said surface of said transparent light guide component, is formed on said reverse face of said transparent light guide component, said reverse face of said transparent light guide component and said reflection component are fixed by welding in a state that said reflection pattern is formed between said reverse face of said transparent light guide component and said reflection component. Therefore, said reflection component can be firmly fixed to said transparent light guide component, and the manufacturing cost can be reduced.
According to a second aspect of the present invention, at a manufacturing method of an area type light emitting device, in which a reflection component is disposed on the reverse face of a transparent light guide component, and also a light source is disposed at the side of said transparent light guide component, makes light emit from the surface of said transparent light guide component by that emitted light from said light source is inputted to said transparent light guide component and said inputted light is reflected on said reflection component and said reflected light is passed through said surface of said transparent light guide component, at the same time when a reflection pattern, which makes said emitted light from said light source reflect to said surface of said transparent light guide component, is formed on said reverse face of said transparent light guide component, said reverse face of said transparent light guide component and said reflection component are fixed by welding in a state that said reflection pattern is formed between said reverse face of said transparent light guide component and said reflection component. Therefore, a process that said reflection component is jointed with said transparent light guide component and a process that said reflection pattern is formed on said transparent light guide component can be unified, consequently, the manufacturing cost can be reduced and said reflection component can be firmly fixed to said transparent light guide component.
According to a third aspect of the present invention, at a manufacturing method of an area type light emitting device, in which a reflection component is disposed on the reverse face of a transparent light guide component, and also a light source is disposed at the side of said transparent light guide component, makes light emit from the surface of said transparent light guide component by that emitted light from said light source is inputted to said transparent light guide component and said inputted light is reflected on said reflection component and said reflected light is passed through said surface of said transparent light guide component, at the same time when said transparent light guide component is molded, a reflection pattern, which makes said emitted light from said light source reflect to said surface of said transparent light guide component, is formed on said reverse face of said transparent light guide component, and said reverse face of said transparent light guide component and said reflection component are fixed by welding in a state that said reflection pattern contacts with said reflection component. Therefore, a process that said reflection pattern is formed on said reverse face of said transparent light guide component is not required, consequently the manufacturing cost can be reduced, and said reflection component can be firmly fixed to said transparent light guide component by welding.